Signal generator



' Feb. 4, 1947. wm 2,415,093

SIGNAL GENERATOR Filed Aug. 3, 1945 Ins-.1;

' 14 HARRY L; GERWIN Patented Feb. 4, 1947 UNITED STATES' PATENT OFFICE 2,415,093 srcner. cnnaim'ron Barry L. Getwin, United States Navy v miicationAulult 3, 1945, Serial No. 808,818

The invention relates to electrical signal gen-- erating circuits. 1

An object of the invention is to provide novel means for generating a group of electrical signal impulses.

Another object of the invention is to provide novel means for generating electrical impulses in tively long time duration and one or more electrical impulses of relatively short time duration.

A further object of the invention is to provide novel means for generating successive electrical impulses comprising single impulses of predetermined time duration and arranged in a predetermined time sequence forming a signal group.

Other objects and features of the invention will appear more fully irom the following detailed description when considered in connection with the accompanying drawing. It is to be expressly understood, however, that the embodiment shown in the drawing is designed for purposes of illustration only and not as a definition oi the limits oi! the invention, reference for the latter purpose being had to the appended claims.

I In the drawing, wherein similar reference characters denote similar parts throughout the several views:

Fig. 1 is a schematic circuit bodiment of the invention;

Fig. 2 shows wave form representative of the voltages at certain parts of the circuit shown in Fig. l, plotted with respect to time.

Referring now more particularly to Fig. 1 there is shown a schematic circuit diagram of an electrical impulse generator embodying the inven tion. Switch tube I is a tetrode of the gaseous type, such as a screen grid thyratron. The control grid 'Ii and screen grid I2 are connected to a source of negative voltage -19 supplying a normally blocking grid potential through resistors 14 and I6 respectively. The anode I1 is connected to one terminal 18 of delay network I9. The latter comprises, in the embodiment shown, an artificial transmission line having a plurality of inductors 8| and a plurality of capacitors 82, Also, the anode TI is connected through a charging resistor 83 to a source of positive voltage 84. The cathode 86 of tube is connected to ground through resistor 81. The other terminal of the artificial transmission line I9 is connected to ground through another-delay network shown as artificial transmission line 9| comprising inductors 92 and capacitors 93. Line 9| is terminated in its characteristic impedance at its other end by a resistor 94 connected between control diagram of an ema group comprising an electrical impulse of rela- 9 Claims. (01. rm-sso) (Granted under the act of March 3, amended April 30, 1928; 370 0. G.

grid 88 and cathode 91 of a normally conducting triode switch tube 88. The anode I00 oi switch tube 98 is connected through resonant circuit 99 comprising inductor IOI and capacitor I02 to resistor I03 which is shunted by by-pass capacitor I04. The other end of resistor I09 is connected to a source 01' positive voltage 84. The control grid I08 of mixing tube I01 is coupled to the plate 01' tube 88 through capacitor I08 and is also connected through resistor I08 to a source or negative bias voltage III. The plate H2 of tube N1 is connected to a source of positive voltage 84. Cathode H3 is connected to the cathode 80 of tube I0 and to the control grid I I4 or amplifier tube I I8. The plate II I of amplifier tube II9 is connected through the primary winding II8 of transformer II9 to a source of positive voltage 84. The input terminals 29 and 30 are connected through capacitors 22 and 23 respectively to the control grid 1| and the screen grid I2 respectively, oi tube 70. Input terminal is connected to ground. The output terminals'9l are connected to the secondary winding I 2I of transformer I I9. Negative grid bias for amplifier tube H6 is developed across resistor I22 connected between cathode I24 and ground. Resistor I22 is shunted by a by-pass condenser I23.

The operation 01' the invention will be explained first with reference to its quiescent condition. In the quiescent condition, when no voltage is: applied to the input terminals 29,30, 35, the flow of plate current through switch tube 10 is cut off due to the negative potential oi. control grid II and screen grid I2. Artificial line I9 is charged through a high resistance 83 to thepotentlal of voltage source 84, Plate current is flowing through tube 98 due to the fact that the grid 98 is at cathode potential, there being no charge on artificial line 9|. The magnitude of the plate current through tube 98 is limited by resistor I03 to a value not in excess of the rated current. of the tube. Plate current or tube I0! is cut oil by the negative bias supplied by source I l I. Resistor I22 is preferably of sufficiently high resistance to bias tube II 6 almost to plate current cut-oil.

The circuit of Fig. 1 becomes operative when the potentials of the control grid 'II and screen grid I2 of gaseous switch tube 10 simultaneously exceed certain critical values. This condition will occur, for example, when a positive voltage impulse of sufiicient magnitude is applied between input terminals 29, 35, and another positive voltage impulse of sufficient magnitude is simultaneously applied between input terminals 30, 35. said impulses are coupled respectively to the contube I I6 is shown by curve ear.

trol grid H and screen grid 12 of tube I0, causing tube 10; to conduct plate current. Referring now to Fig. 2. tube 10 starts conducting plate current in at time it, said plate current being supplied principally by the discharge of artificial line 19.

The plate current in fiows through the circuit impedance of the line 19. At a later time, is, when line 19 has completely discharged, the plate voltage of tube 10 drops below the minimum value necessary to maintain plate current conduction and plate current flow is cut off abruptly. The magnitude d1 of the time interval between t1 and i2 is determined, in a manner known to those skilled in the art, by the magnitudes of the inductance 8| and capacitance 82 of each section of line 79 and the number of sections composing the line, each section comprising one inductor 8| and one capacitor 82. The flow of current in through resistor 81 causes a positive voltage impulse of a duration d1 to be applied to the cathode H3 of tube l! and to'the grid llflof tube H6. The waveform of thevoltage at the grid N4 of Similarly, the fiow of current in into artificial line 9| produces a negative impulse of voltage across the line 9|. This negative impulse is delayed by an. amount of time 12 as it travels along artificial line 9| to the grid of tube 98. Artificial line 9| thus functions as a delay device and is designed to have a delay time (12 greater than the duration d1 of the discharge time of line I9. Consequently, a negative voltage impulse of duration d1 reaches the grid 96 of tube 98 at time is. The magnitude of the impulse is sufiicient to cut oil the flow of plate current through tube 98. The abrupt interruption of plate current through tube 98 initiates damped oscillations in resonant circuit 99, beginning at time is. The oscillatory voltage of the resonant circuit is applied through coupling condenser I98 to the grid I06 of tube ||l|. The voltage waveform at the grid I06 is shown by curve em. The applied oscillatory voltage is superimposed on the negative D. C. bias from source causing the grid I06 to rise periodically above the plate current cut-ofi potential during a portion of each positive half cycle of the oscillatory voltage. Thus, short impulses of plate current flow through tube |l and resistor 81 for a time interval (11 between ta and t4. The resulting short voltage impulses at cathode H3 are applied to the grid H4 of tube H6. At time t4, the voltage ese of tube 98 rises to zero and tube 98 conducts plate current, thus quickly damping the oscillations of resonant circuit 99.

There is thus produced at the grid H4 of tube ||6 a group of voltage impulses as shown by thecurve em, Fig. 3, in which an impulse of relatively I long duration is followed by two impulses of relatively short duration. It will be understood that the number of short impulses in each group is determined by the natural frequency of the resonant circuit 99, and the duration 121 of the relatively long impulse. The number of short impulses in each group is:

N ==fn l where fn is the natural frequency of the resonant circuit.

The impulses are amplified by tube H6 and may be applied to the output terminals 3| of the circuit through an impedance matching transformer H9.

It should be understood that the practice of the invention is not limited to the embodiments illustrated and described but is circumscribed onlyv by the scope and limitations of the appended claims. v

The invention described herein may be manufactured and used by or for the Government of the United states of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim: 1. A voltage signal source comprising an artificial line, means for shiftingthe potential of said line to generate a signal, time delay transmission mean receiving said signal, a signal generator, means for initiating the operation of said signal generator responsive to the delayed transm'itted signal, and mixer means coupled to said artificial line and to said signal generator.

2. A voltage signal source comprising an artificial line, mean for charging said line, means for discharging said line to generate a signal,

time delay transmission means receiving said signal, a signal generator, means for initiating the operation of the signal generator responsive to the delayed transmitted signal, and mixer mean coupled to said line and to said signal generator.

3. A voltage signal source comprising a first artificial, line, means for charging said line, a second artificial line, means for discharging the first line across the second line, a signal generator, means for initiating operation of the signal generator subsequent to initiation of discharge of the first line becoming operative responsively to termination of the signal delivered through the second line from discharge of the first line to terminate operation of the signal generator, and mixer means coupled to the first line and to the signal generator.

4. A voltage signal source comprising a first artificial transmission line, means for charging said line, a second artificial transmission line, means for discharging the first line across the second line, a signal generator, means initiating operation of the signal generator operative responsively to delivery of the signal from discharge of the first line through the second line, and mixer means coupled to the first line and I to the signal generator.

5. A voltage signal source comprising a first artificial transmission line, means for charging said line," a second artificial transmission line, means for discharging the first line across the second line, a discrete signal generator, means initiating operation of the signal generator operative responsively to delivery of the signal from discharge of the first line through the second-line and becoming operative after a time interval in dependency on termination of the discharge of the first line to terminate operation of the discrete signal generator, and mixer means coupled to the first line and to the signal generator.

6. A voltage signal source comprising a first artificial transmission line, means for charging said line, a second artificial transmission line,. means for discharging the first line across the second line, a discrete signal generator operative to supply a plurality of signal pulses, means initiating the operation of the signal generator operative responsively to delivery of the signal from discharge of the first line through the sec- 5 0nd line, and mixer means coupled to the first line and to the signal generator.

7. A voltage signal source comprising a first artificial transmission line, a second artificial transmission line, means for-generating oscillations, means for initiating generation of oscilla-- tions responsively to delivery of the signal from discharge of the first line through the second line, and mixer means coupled to the first line and to the signal generat0r.,

8, A voltage signal source, comprising a first artificial transmission line, means for charging said line, a second artificial transmission line, means for discharging the first line across the second line, a discrete signal generator operative to supply a plurality or signal pulses, means initiating the operation of the signal generator operativeresponslvely to delivery of the signal from discharge of the first line through the second line and becoming operative after a timezo interval in dependency on termination of the discharge of the first line .to terminate operation of the discrete signal generator, and mixer means coupled to the first line and to the signal generator.. n

9. Means for generating a group of electrical impulses comprising an impulse of relatively long time duration and one or more impulses of relatively short time duration-including an artificial transmission line, means operative to shift the potential of said line to generate an initial impulse of relatively long time duration, a resonant circuit for generating impulses of relatively short time duration, and means coupling said line to said resonant circuit operative to excite said resonant circuit subsequent to termination of said initial impulse to generate impulses of relatively short time duration, and mixer means coupled to said li e and HARRY L. GERWIN.

to said resonant circuit. 

